CH Navigation & Nautical Chart Production

Question 1

What is the primary horizontal datum used for nautical charts produced by NOAA in the United States?

Accepted Answer

NAD 83 / WGS 84

Answer

NAD 27

Answer

ED 50

Answer

ITRF 2014

Question 2

On a nautical chart, a sounding value shown in italics typically indicates:

Accepted Answer

A depth that is less reliable or obtained from an older survey

Answer

A depth measured by lead-line rather than echo sounder

Answer

A reef or rock awash at chart datum

Answer

A depth corrected for tide at time of survey

Question 3

What does the chart symbol 'Wk' followed by a dashed outline indicate on a nautical chart?

Accepted Answer

A wreck whose position is approximate or unsurveyed

Answer

A waypoint for recommended anchorage

Answer

A water intake structure

Answer

A well-surveyed wreck cleared to a known depth

Question 4

The Mercator projection used for most nautical charts preserves which property?

Accepted Answer

True compass bearings (rhumb lines appear as straight lines)

Answer

Equal area across all latitudes

Answer

Great circle routes as straight lines

Answer

Accurate representation of polar regions

Question 5

Which vertical datum is used as the reference surface for depths (soundings) on NOAA nautical charts in US waters?

Accepted Answer

Mean Lower Low Water (MLLW)

Answer

Mean Higher High Water (MHHW)

Answer

Mean Sea Level (MSL)

Answer

National Geodetic Vertical Datum 1929 (NGVD 29)

Question 6

The term 'Least Depth' on a chart refers to:

Accepted Answer

The minimum depth over a specific feature such as a shoal or wreck

Answer

The shallowest depth in a channel approach

Answer

The depth at the channel centerline during low tide

Answer

The depth below which anchoring is prohibited